Neuropsychological perspectives on the mechanisms of imitation

Abstract

Cognitive neuroscientists have contributed to the understanding of imitation according to their expertise. Neuropsychologists first established over a century ago that lesions to the left hemisphere of right-handed individuals lead to a dramatic reduction of their ability to imitate gestures. In contrast, after frontal lobe damage, patients may experience severe difficulties in inhibiting their imitative tendency. These findings suggested that our tendency to imitate is mostly sustained by the left hemisphere and that we normally manage successfully to keep it under control. Neuropsychologists went on investigating other aspects of gesture imitation. These include the existence of putative mechanisms involved in imitating different types of gestures (e.g. meaningful and meaningless or transitive and intransitive), the strategic control over these mechanisms and whether there are differences in imitation depending on the action goal or the body part used. Based on neuropsychological findings, some cognitive models of gesture imitation have been forwarded, the most influential of which will be reviewed here. In particular, reference will be made to the dual route model and to accounts that associate the imitative deficit to putative degraded body representations.

Imitation Assessment and Its Utility to the Diagnosis of Autism: Evidence from Consecutive Clinical Preschool Referrals for Suspected Autism

“…Results of brain imaging studies in healthy adults revealed two distinctive routes of imitation depending on the representational level of the actions. The imitation of actions of which the meaning or goal can only be identified retrospectively relies on a direct route, which transforms visuospatial characteristics into motor representations (Rumiati et al 2005(Rumiati et al , 2009Tessari and Rumiati 2004). Children may use this direct route of imitation to copy the non-meaningful bodily actions and the non-goal directed actions upon objects of the PIPS.…”

“…They may faithfully copy the observable motor organisation of the demonstrator's act, i. e. the movement itself (the means) and the movement effect (the result). The imitation of familiar actions, for which the observer can identify a meaning or a goal and possesses a template in the long-term memory, relies on an indirect semantic-related route of imitation (Rumiati et al 2005(Rumiati et al , 2009Tessari and Rumiati 2004). Children may use this indirect route of imitation to copy the meaningful bodily actions and goal directed actions upon objects of the PIPS.…”

Associative sequence learning: the role of experience in the development of imitation and the mirror system

“…Whereas most contemporary theories emphasize the importance of mindsets (van Baaren et al 2009), or of strategic (Rumiati et al 2009), intentional (Massen & Prinz 2009) or rational (Gergely et al 2002) processes in guiding imitative behaviour, the ASL model stresses automaticity. It suggests that, once a vertical association has been formed between a sensory and a motor representation of action, activation of the sensory component inevitably results in activation of the motor component (Heyes & Bird 2007).…”

“…Studies of neuropsychological patients suggest a role for the mirror system in imitation (see also Rumiati et al 2009), but they do not make clear which areas within the mirror system are critical. Lesions to the inferior parietal lobe, particularly in the left hemisphere, often result in apraxia-a deficit in miming gestures and in imitation (Wheaton & Hallett 2007).…”

Imitation as an inheritance system

“…Such abilities presuppose that the individual has a capacity that delivers correspondences between what is perceived and how they can act, but correspondence mechanisms should not be equated with the kinds of imitation that are candidates to form an inheritance system. Rumiati et al (2009) review the long history of neuropsychological evidence that substantiates a similar distinction between two kinds of neural mechanisms. One mechanism is the basis on which people respond to perceptual stimuli by having an idea of a corresponding movement (similar to the correspondence mechanism discussed above).…”